Environment Canada says it alerted residents of Durham half an hour before a tornado struck their small town.
The F-2 tornado that hit last Thursday afternoon is suspected to have caused between 7.5 million and 9 million dollars in damage.
Toronto-based storm chaser Mark Robinson says there are problems with how warnings are communicated to the public.
He says there is not enough infrastructure in place to get the message to everyone.
The tornadoes — which struck several Ontario communities last week — were blamed for the death of 11 year old Owen McPherson of Ayton.
Ontario Premier Dalton McGuinty says authorities should look at how they could better warn the public about tornadoes in the wake of a deadly storm last week.
McGuinty says the government has a responsibility to look at what lessons can be learned in the aftermath of such a crisis.
He says if there are better weather warning systems in place elsewhere, authorities have a duty to take a look at them.
McGuinty’s comments come amid concerns that a tornado warning before the killer storm hit Ontario failed to reach emergency services and those who needed it most.